EARLIER STUDIES BY THIS INVESTIGATOR SHOWED THAT VERAPAMIL AND DILTIAZEM (SLOW CA2+ CHANNEL BLOCKERS) EFFECTIVELY BLOCKED ACH-INDUCED CONTRACTIONS IN MECHANICAL STUDIES. AT THE NVPF CA2+ MOVEMENT ACROSS THE MEMBRANE OF ECHINODERM SMOOTH MUSCLE IN RESPONSE TO ACH AND THE TWO ANTI-HYPERTENSIVE DRUGS, VERAPAMIL AND DILTIAZEM, WAS STUDIED USING A NON-INVASIVE CA2+ -SELECTIVE PROBE. THE TECHNIQUE~S EFFICACY IN RECORDING CURRENTS FROM INVERTEBRATE MUSCLE WAS ALSO TESTED. DUE TO THE STRAP-LIKE CONFIGURATION OF MUSCLE BUNDLES, THIS METHOD WAS FOUND TO BE IDEAL FOR SCANNING CURRENT ACTIVITY DOWN THE LENGTH OF ENTIRE MUSCLE CELLS WITHOUT PHYSICALLY CONTACTING OR DAMAGING THE INDIVIDUAL CELLS. THIS STUDY ALSO SHOWED THAT CLINICALLY USED CA2+ ANTAGONISTIC DRUGS SUCH AS DILTIAZEM AND VERAPAMIL ELICIT PHYSIOLOGICAL RESPONSES IN INVERTEBRATE MUSCLE WHICH SUGGESTS SOME DEGREE OF HOMOLOGY BETWEEN CA2+ CHANNELS IN MAMMALIAN AND INVERTEBRATE MUSCLE. DR. DEVLIN WILL CONTINUE THESE AND RELATED STUDIES DURING THE SUMMER OF 1995 FUNDED BY AN MBL FELLOWSHIP, SEE SUBPROPOSAL III A-12.